Discrete potentials guided radiofrequency ablation for idiopathic outflow tract ventricular arrhythmias

Unipolar and bipolar electrogram characteristics of recurrent cases of idiopathic ventricular arrhythmias undergoing repeat catheter ablation

Introduction

Activation mapping guided catheter ablation (CA) of ventricular arrhythmias (VAs) is limited in some cases when it is only relied on bipolar electrogram (EGM). We hypothesized that activation mapping with use of combined bipolar and unipolar EGM facilitates to identify the focal origin of VAs and results in reduction of recurrence rate of CA of VAs.

Methods

We analyzed the data of patients undergoing repeat ablations for idiopathic out-flow tract VAs. The EGM of the 1 st and 2 nd ablations were compared for earliest local activation time (LAT), presence of discrete potentials, and polarity reversal, unipolar potential morphology (QS or non-QS), potential amplitude and activation slope.

Results

Thirty-seven patients were included. The Local activation time was significantly earlier in the 2nd ablation as compared to the 1st procedure (36.90 msec vs 31.85 msec, P < 0.01). The incidence of discrete potentials and polarity reversal were similar in both procedures (51% vs 57%, P = 0.8 and 62% in both the occasions, respectively). The unipolar voltage was similar in both occasions (6.94 mV vs 7.22 mV in repeat ablations, P = 0.7). The recurrence rate (5.7%) was significantly lower with routine use of combined unipolar and bipolar EGMs, as compared to the use of bipolar EGM alone (16.7%)

Conclusions

Use of both bipolar and unipolar electrograms helps in better delineation of the sites of earliest activation for effective ablation of VAs. Use of unipolar electrograms in addition to bipolar electrograms is associated with lower long term recurrence rate.

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In patients undergoing redo ablations for idiopathic OTVAs, a slow-rapid initial QS morphology with its earlier timing prior to onset of QRS on unipolar EGM facilitate identification of early activation sites and improves success of CA.

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Bipolar EGM chracteristics like polarity reversal and presence of discrete potentials have no additive efficacy in redo CA cases.

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A slow-rapid initial QS morphology with its earlier timing to QRS onset may improve the success of CA in idiopathic OTVAs.

Catheter ablation of premature ventricular contractions originating from periprosthetic aortic valve regions

BACKGROUND

Little is known about the ablation outcomes of premature ventricular contractions (PVCs) that originate from the periprosthetic aortic valve (PPAV) regions of patients with aortic valve replacement (AVR).

METHODS AND RESULTS

Our study had 11 patients who underwent catheter ablation for PVCs arising from the PPAV regions (bioprosthetic aortic valve, n = 5; mechanical aortic valve, n = 6). The PVC characteristics, procedure characteristics, and efficacy of ablation were compared with the control group (n = 33). At baseline, the PPAV group had a lower left ventricular ejection fraction (mean [SD], 41% [12%] vs. 51% [8%]; p = .002). The rate of acute ablation success was 90.9% in the PPAV group. Ablation sites were identified above the left coronary cusp (LCC) and right coronary cusp commissure (LRCC) in one PVC, below the prosthetic valve in eight PVCs (four below LCC and four below LRCC), and within the distal coronary sinus in two PVCs. The mean procedure time, fluoroscopy time, and radiation in the PPAV group were all significantly greater than those in the control group (all p < .05). However, the number of radiofrequency ablation energy deliveries was not different. The PPAV group had a long-term success rate compared with the control group (72.7% vs. 87.9%, p = .48) and an increase of left ventricular ejection fraction from 43% to 49% after successful PVC ablation at follow-up (p < .001). Echocardiography showed no significant change in valve regurgitation after ablation. No new atrioventricular block occurred.

CONCLUSION

PVCs arising from PPAV regions can be successfully ablated in patients with prior AVR, without damaging the prosthetic aortic valve and atrioventricular conduction.

Implication of the distinctive bipolar intracardiac electrograms for ventricular arrhythmias arising from different regions of ventricular outflow tract

AIMS

To investigate the characteristics of bipolar intracardiac electrograms (bi-EGMs) in target sites of ventricular arrhythmias (VAs) originating from different regions of ventricular outflow tract (VOT).

METHODS AND RESULTS

Two hundred and seventy patients undergoing first-time ablation for VAs originated from distal great cardiac vein (DGCV), aortic sinus cusps (ASCs), or pulmonary sinus cusps (PSCs) were enrolled in present study. Local intracardiac bipolar recordings on 243 successful sites and 506 attempted but unsuccessful ablation sites were analysed. Specific potentials in bi-EGMs on successful sites were more common compared with unsuccessful sites (76.95%, 187/243 vs. 25.49%, 129/506, P < 0.05). A total of 60.00% (81/135) patients in ASCs group presented a presystolic short-duration fractionated potential, higher than 23.21% (13/56) in DGCV and 23.08% (12/52) in PSCs (all P < 0.05); 44.23% (23/52) patients in PSC group showed a presystolic high-amplitude discrete potential, while 1.79% (1/56) in DGCV and 2.22% (3/135) in ASCs (all P < 0.05); 41.07% (23/56) patients in DGCV group showed bi-EGMs of presystolic long-duration multicomponent fractionated potential, which was significantly higher than 3.85% (2/52) in PSCs and 4.44%(6/135) in ASCs (all P < 0.05).

CONCLUSION

Distinctive morphology of bi-EGMs during VAs can be found in different regions of VOT, which probably due to changes in the arrangements of myocardial sleeves. Correct identification and better understanding of the distinctive features of these bi-EGMs with regards to the anatomic location was important, the presence of specific potentials may add help in successful ablation.

Mapping and Ablation of Ventricular Outflow Tract Arrhythmias

Arrhythmias arising from the ventricular outflow tracts are commonly encountered. Although largely benign, they can also present with heart failure and sudden cardiac death. Mapping and ablation of these arrhythmias is commonly performed in the electrophysiology laboratory with a high success rate, but occasionally can prove challenging to abolish. This article discusses the mapping and ablation of outflow tract arrhythmias and the challenges that can be overcome by a systematic approach.

Catheter-induced premature ventricular complexes (PVCs) may aid in the determination of optimal timing for clinical PVC ablation

BACKGROUND

The aim of the present study is to evaluate whether catheter-induced premature ventricular complexes (PVCs) produced at the presumptive ablation site may aid in the identification of the optimal timing of the earliest local activation for the successful ablation of clinical PVCs.

METHODS

Sixty-three consecutive patients (35 males, age: 53.5 ± 14.4 years) without any exclusion criteria who had undergone PVC ablation between 1 July 2018 and 1 July 2019 constituted our study population. The time interval between the beginning of the EGM and the beginning of the QRS of each catheter-induced PVC (Cath EGM-ECG) and the time interval between the beginning of the EGM of clinical PVCs at the earliest site and the beginning of the QRS of clinical PVCs (PVC earliest EGM-ECG) were noted for each patient. The value of Cath EGM-ECG as a reference for procedural success of ablation was evaluated by examining the relationship between Cath EGM-ECG and PVC earliest EGM-ECG.

RESULTS

Fifty-two patients had successful ablation, and 43 of them (82.7%) had PVC earliest EGM-ECG values greater than or equal to Cath EGM-ECG. Eleven patients had procedural failure, and all of them had PVC earliest EGM-ECG values lower than Cath EGM-ECG. A PVC earliest EGM-ECG value -1.5 ms greater than Cath EGM-ECG predicted successful ablation with a sensitivity of 90.4% and a specificity of 100.0% in the general patient population.

CONCLUSION

Cath EGM-ECG seems to serve as a reliable guide for finding the optimal timing of the earliest site for successful PVC ablation.

The V1-V3 transition index as a novel electrocardiographic criterion for differentiating left from right ventricular outflow tract ventricular arrhythmias

PURPOSE

The aim of this study was to develop a new electrocardiographic criterion for differentiating the origin of outflow tract ventricular arrhythmias (OT-VAs) with precordial transition in lead V₃.

METHODS

A total of 147 consecutive patients with OT-VAs displaying precordial transition in lead V₃ who underwent successful catheter ablation in the right ventricular outflow tract (RVOT) (n = 118) or left ventricular outflow tract (LVOT) (n = 29) were included in this study. The V₁-V₃ transition index was defined as the sum of S-wave amplitude in lead V₁ and V₂ during premature ventricular contractions (PVCs) divided by the S-wave amplitude during sinus rhythm (SR), respectively, minus the sum of R-wave amplitude in lead V₁, V₂, and V₃ during PVCs divided by the R-wave amplitude during SR, respectively, i.e., [(S_PVC/S_SR)V₁ + (S_PVC/S_SR)V₂] - [(R_PVC/R_SR) V₁ + (R_PVC/R_SR)V₂ + (R_PVC/R_SR)V₃].

RESULTS

The V₁-V₃ transition index was significantly higher for RVOT origins than for LVOT origins (1.25 ± 2.48 vs. - 3.94 ± 3.11; P < 0.001). Receiver operating characteristic (ROC) analysis revealed an area under the curve (AUC) of 0.931 for the V₁-V₃ transition index, and a cutoff value of > - 1.60 predicted a RVOT origin with a 93% sensitivity and 86% specificity. With respect to AUC and accuracy, the V₁-V₃ transition index was superior to any previously proposed ECG indices for differentiating left from right OT-VAs. In 37 prospective cases, the new index was able to predict the site of a RVOT origin with 95% accuracy (35 of 37 cases).

CONCLUSIONS

The V₁-V₃ transition index is a useful novel ECG criterion for distinguishing left from right OT-VAs with precordial transition in lead V₃.

Late fractionated potentials in catheter ablation for right ventricular outflow tract ventricular arrhythmias

BACKGROUND

Endocardial late fractionated potentials during sinus rhythm mapping may reflect abnormal "subendocardial" substrates associated with right ventricular outflow tract (RVOT) ventricular arrhythmias (VAs). The aim of this study was to explore the clinical outcomes of catheter ablation guided by these late fractionated potentials for RVOT VAs in patients without structural heart disease.

METHODS

From January 2016 to March 2018, 28 patients underwent catheter ablation for RVOT premature ventricular contractions (PVCs) or ventricular tachycardia (VT), guided by the EnSite NavX or Velocity V5.0 three-dimensional mapping system (Abbott, St. Paul, MN, USA). Among them, 10 patients (35.7%) were found to have endocardial late fractionated potentials during sinus rhythm mapping (Group 1). Group 2 was composed of 18 patients in whom no endocardial late fractionated potentials were seen. The burden of VAs, acute procedural success, and 3-month clinical outcomes were analyzed.

RESULTS

The average duration of late fractionated potentials after the end of QRS during sinus rhythm mapping in group 1 was 45.00 ± 17.15 ms. Baseline demographics and morphology and burden of PVCs were similarly distributed between both groups. Group 1 had higher acute procedural success compared to group 2 (100% vs 66.7%; P = .039). Moreover, at 3-month follow-up, group 1 had lower total PVCs (49 (1-5986) versus 4316 (1-23231); P = .048), PVC burden (0% (0-5.9) vs 4.3% (0-18.9); P = .055), and higher clinical success (100% vs 55.6%; P = .025) compared to group 2.

CONCLUSION

The identification and elimination of endocardial late fractionated potentials during sinus rhythm mapping could improve the acute success and short-term outcomes of ablation for RVOT VAs.

Isolated diastolic potentials as predictors of success in ablation of right ventricular outflow tract idiopathic premature ventricular contractions

BACKGROUND AND AIMS

Discrete potentials, low voltage and fragmented electrograms, have been previously reported at ablation site, in patients with premature ventricular contractions (PVCs) originating in the right ventricular outflow tract (RVOT). The aim of this study was to review the electrograms at ablation site and assess the presence of diastolic potentials and their association with success.

METHODS

We retrospectively reviewed the electrograms obtained at the radiofrequency (RF) delivery sites of 48 patients subjected to ablation of RVOT frequent PVCs. We assessed the duration and amplitude of local electrogram, local activation time, and presence of diastolic potentials and fragmented electrograms.

RESULTS

We reviewed 134 electrograms, median 2 (1-4) per patient. Success was achieved in 40 patients (83%). At successful sites the local activation time was earlier- 54 (-35 to -77) ms vs -26 (-12 to -35) ms, p<0.0001; the local electrogram had lower amplitude 1 (0.45-1.15) vs 1.5 (0.5-2.1) mV, p = 0.006, and longer duration 106 (80-154) vs 74 (60-90) ms, p<0.0001. Diastolic potentials and fragmented electrograms were more frequently present, respectively 76% vs 9%, p <0.0001 and 54% vs 11%, p<0.0001. In univariable analysis these variables were all associated with success. In multivariable analysis only the presence of diastolic potentials [OR 15.5 (95% CI: 3.92-61.2; p<0.0001)], and the value of local activation time [OR 1.11 (95% CI: 1.049-1.172 p<0.0001)], were significantly associated with success.

CONCLUSION

In this group of patients the presence of diastolic potentials at the ablation site was associated with success.

Idiopathic Ventricular Premature Contraction and Ventricular Tachycardia: Distribution of the Origin, Diagnostic Algorithm, and Catheter Ablation

Idiopathic ventricular premature contractions (VPCs), defined as VPCs in the absence of obvious structural heart disease, are one of the common types of arrhythmia in clinical practice. They are sometimes complicated with non-sustained ventricular tachycardia (VT), and/or sustained VT with almost same QRS morphology in 12 leads ECG. Idiopathic VT (IVT) commonly occurs by focal mechanisms and the origins are distributed in a variety of sites in both ventricles. In this article, the clinical characteristics of IVT/IVPCs, the diagnostic algorithm, and how to ablate them will be reviewed.

Ablation of the vanishing PVC, facilitated by quantitative morphology-matching software

BACKGROUND

Ablation of cardiac arrhythmias in children and teenagers often necessitates the use of anesthesia, which can suppress ventricular arrhythmias (VAs), making it difficult to map the site of origin using activation time (AT). Pace mapping, a technique employed to assist with VA origin localization, depends on subjective comparison of paced and targeted QRS morphology. We assessed the utility of a quantitative approach to paced QRS to VA morphology matching using the PaSo software (Carto 3, Biosense Webster), to localize the VA site of origin.

METHODS

Twenty-four patients underwent 26 procedures for frequent VAs, 29 for targeted VA. If AT mapping was precluded due to infrequent VA, pace mapping was executed using the PaSo software, after regionalization based on targeted VA QRS morphology.

RESULTS

Subjects were aged 1-32 (mean 14 ± 6) years; 10 were male. Heart disease was present in six patients. PVC frequency prior to onset of anesthesia was 15 ± 16/min, decreasing to 0-1 PVC/min in 17 cases prior to ablation. Arrhythmia localization was performed by AT mapping + PaSo (12) or PaSo only (17). Pace mapping exhibited an intraventricular gradient of percent QRS morphology match. Highest achieved QRS match averaged 96 ± 2%. Successful ablation (> 1-month follow-up) was achieved in 24/29 targeted VAs, 11/12 ablated using AT and pace mapping, and 13/17 VA ablated using pace mapping only, P  =  0.29.

CONCLUSIONS

(1) Spontaneous VA frequency was markedly reduced following anesthesia, despite catecholamine administration. (2) Notwithstanding the ability to perform AT mapping, successful ablation can still be performed using pace mapping only, facilitated by the PaSo software.